Radiative cooling systems

ABSTRACT

A material may be included in a cooling film or cooling panel to achieve cooling even under direct solar irradiation. The material includes one or more constituent materials and an outer surface configured to interact thermally with the atmosphere and with solar radiation. The material exhibits an emissivity of at least 0.8 in spectral range of 5 μm to 15 μm, an ultraviolet reflectivity of at least 0.5 in the spectral range of 275 nm to 375 nm, an ultraviolet absorptivity of at least 0.75 in the spectral range of 275 nm to 375 nm, or a combination thereof. A cooling film, or cooling panel, may be affixed to an exterior surface of a vehicle, structure, or system to provide cooling even under direct solar irradiance.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/852,132 filed on Apr. 17, 2020, which claims the benefit of U.S.Provisional Patent Application No. 62/835,411 filed Apr. 17, 2019, thedisclosures of which are hereby incorporated by reference herein intheir entireties.

BACKGROUND

One challenge radiative cooling materials face is their long-termexposure because they are arranged outdoors to enable the radiativecooling effect. For example, durability under both sunlight andweathering conditions poses a central challenge to the effectiveness ofa cooling panel.

SUMMARY

The present disclosure is directed to materials, films, cooling panels,and cooling systems. In some embodiments, the present disclosure isdirected to a material for radiative cooling that includes one or moreconstituent materials, an outer surface configured to interact thermallywith the atmosphere and with solar radiation, and a thermal emissivityof at least 0.8 in spectral range of 5 μm to 15 μm. The materialexhibits strong ultraviolet absorption or reflection in the spectralrange of 275 nm to 375 nm. In some embodiments, the material includes anemissivity of at least 0.8 in spectral range of 5 μm to 15 μm, anultraviolet reflectivity of at least 0.5 in the spectral range of 275 nmto 375 nm, an ultraviolet absorptivity of at least 0.75 in the spectralrange of 275 nm to 375 nm, or a combination thereof. For example, insome embodiments, the material includes ZnO, Si, HfO2, ZnO2, or acombination thereof. In some embodiments, the material is capable ofachieving a cooling rate of at least 10 W/m2 at 300 K when exposed tothe sky at a 300 K ambient air temperature. In some embodiments, thematerial includes a thickness substantially normal to the outer surface.In some embodiments, the material includes a top layer nearest the outersurface simultaneously provides strong thermal emittance and high UVabsorption. In some embodiments, the material includes a top layernearest the outer surface simultaneously provides strong thermalemittance and high UV reflectance. In some embodiments, the material iscapable of reflecting greater than 93% of the weighted solar spectrumfrom 300 nm to 4 μm in free-space wavelength. In some embodiments, thematerial includes a plurality of discrete planar layers along a depthdimension. The layers may include a top layer exhibiting thermalemissivity averaged at greater than 0.8 from 7 μm to 15 μm inwavelength, and a lower layer designed to exhibit strong solar spectrumreflection from 300 nm to 4 μm. For example, the material may include anemissivity of at least 0.8 in spectral range of 5 μm to 15 μm, anultraviolet reflectivity of at least 0.5 in the spectral range of 275 nmto 375 nm, an ultraviolet absorptivity of at least 0.75 in the spectralrange of 275 nm to 375 nm, or a combination thereof. In someembodiments, the material is capable of absorbing at least some of thevisible spectrum of 400 nm to 900 nm to enable a visual color.

In some embodiments, the present disclosure is directed to a coolingassembly that includes a panel and a heat exchanger. The panel includesone or more constituent materials, and an outer surface configured tointeract thermally with the atmosphere and with solar radiation. Thepanel includes an emissivity of at least 0.8 in spectral range of 5 μmto 15 μm, an ultraviolet reflectivity of at least 0.5 in the spectralrange of 275 nm to 375 nm, an ultraviolet absorptivity of at least 0.75in the spectral range of 275 nm to 375 nm, or a combination thereof. Theheat exchanger is affixed to the panel to cool a liquid or gas. In someembodiments, the cooling assembly includes an enclosure configured toinsulate the panel to enable cooling to temperatures further than 3° C.below an ambient air temperature. In some embodiments, the coolingassembly is configured to be affixed to a top of a roof to providedurable cooling to an underlying structure or building. In someembodiments, the cooling assembly is configured to be affixed to a roadtransport vehicle to provide durable cooling to the vehicle whilestationary or in motion.

In some embodiments, the present disclosure is direct to a coolingmaterial configured to facilitate thermally-generated emissions thatoriginate from the material with an averaged thermal emissivity ofgreater than 0.8 in the spectral wavelength range of 7 μm-15 μm, absorbor reflect solar light in the spectral wavelength range of 275 nm to 375nm to minimize damage due to sunlight, and reflect or absorb at leastsome of the solar spectrum from 375 nm to 4 μm to enable visual color.In some embodiment, the material includes an emissivity of at least 0.8in spectral range of 5 μm to 15 μm, an ultraviolet reflectivity of atleast 0.5 in the spectral range of 275 nm to 375 nm, an ultravioletabsorptivity of at least 0.75 in the spectral range of 275 nm to 375 nm,or a combination thereof. In some embodiments, the cooling material isconfigured to be integrated with a heat exchanger to cool a liquid, gasor solid by conductive or convective heat transfer. In some embodiments,the cooling material is configured to cool refrigerant in avapor-compression cycle. In some embodiments, the cooling material isconfigured to achieve a cooling rate greater than 10 W/m2 of net heatrejection at an ambient air temperature during the day or night. In someembodiments, the cooling material is configured to cool a building,structure or vehicle by direct thermal contact with the building,structure or vehicle. In some embodiments, the cooling material isconfigured to enable free convective cooling to cool heat loads from atemperature above an ambient air temperature to the ambient airtemperature. In some embodiments, the cooling material is configured tocool a fluid from the outlet of a component 0.5° C. below or furtherbelow an inlet temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure, in accordance with one or more variousembodiments, is described in detail with reference to the followingfigures. The drawings are provided for purposes of illustration only andmerely depict typical or example embodiments. These drawings areprovided to facilitate an understanding of the concepts disclosed hereinand shall not be considered limiting of the breadth, scope, orapplicability of these concepts. It should be noted that for clarity andease of illustration these drawings are not necessarily made to scale.

FIG. 1 shows a cross-sectional view of an illustrative cooling panelexperiencing incident radiation, and reflecting some of the incidentradiation, in accordance with some embodiments of the presentdisclosure;

FIG. 2 shows a cross-sectional view of an illustrative cooling panelemitting thermal radiation, in accordance with some embodiments of thepresent disclosure;

FIG. 3 shows a cross-sectional view of an illustrative cooling panelabsorbing incident radiation in the visible spectrum, in accordance withsome embodiments of the present disclosure;

FIG. 4 shows a cross-sectional view of an illustrative cooling panelabsorbing or reflecting incident radiation in the spectral range of275-375 nm, in accordance with some embodiments of the presentdisclosure;

FIG. 5 shows a cross-sectional view of an illustrative cooling panelconfigured to accept a heat input from a cooling load, in accordancewith some embodiments of the present disclosure;

FIG. 6 shows a cross-sectional view of an illustrative cooling panelconfigured to reject 10 W/m2 from a cooling load when the panel isexposed to the sky, in accordance with some embodiments of the presentdisclosure;

FIG. 7 shows a cross-sectional view of a cooling panel including twolayers; a UV absorbing or reflecting layer and a thermally emissivelayer, in accordance with some embodiments of the present disclosure;

FIG. 8 shows a cross-sectional view of a cooling panel including twolayers; a UV absorbing or reflecting composite layer and a thermallyemissive layer, in accordance with some embodiments of the presentdisclosure;

FIG. 9 shows a plot exhibiting several cooling curves, in accordancewith some embodiments of the present disclosure;

FIG. 10 shows an illustrative configurations of cooling panels and aheat exchanger, in accordance with some embodiments of the presentdisclosure;

FIG. 11 shows an illustrative configurations of a cooling panel affixedto a heat exchanger, in accordance with some embodiments of the presentdisclosure;

FIG. 12 shows several illustrative configurations of cooling panelsaffixed to vehicles, in accordance with some embodiments of the presentdisclosure;

FIG. 13 shows a side view and top view of a greenhouse havingillustrative cooling panels affixed to the roof, in accordance with someembodiments of the present disclosure;

FIG. 14 shows a side view of an electrical system having illustrativecooling panels affixed to electrical cabinets, in accordance with someembodiments of the present disclosure;

FIG. 15 shows a side view of an outdoor structure having illustrativecooling panels affixed to a roof, in accordance with some embodiments ofthe present disclosure;

FIG. 16 shows a side view of a containerized living unit havingillustrative cooling panels affixed to the exterior, in accordance withsome embodiments of the present disclosure;

FIG. 17 shows several configurations of cooling panels used to coolaspects of a vending machine, in accordance with some embodiments of thepresent disclosure; and

FIG. 18 shows two illustrative configurations of cooling panels used tocool aspects of a swimming pool, in accordance with some embodiments ofthe present disclosure.

DETAILED DESCRIPTION

The present disclosure is directed to materials and configurations thatenable durable radiative cooling that can last a sufficiently long timefor real world cooling applications during both daytime and nighttime.

FIG. 1 shows a cross-sectional view of illustrative cooling panel 101experiencing incident radiation, and reflecting some of the incidentradiation, in accordance with some embodiments of the presentdisclosure. In some embodiments, a material of cooling panel 101 isconfigured to reflect a majority of the solar spectrum from 300 nm to 4μm in free-space wavelength. In some embodiments, a material of coolingpanel 101 is configured to present average reflectance of at least 0.8from 300 nm to 4 μm in free-space wavelength.

FIG. 2 shows a cross-sectional view of illustrative cooling panel 201emitting thermal radiation, in accordance with some embodiments of thepresent disclosure. In some embodiments, the one or more constituentmaterials of cooling panel 201 includes a thermal emissivity (e.g.,average or effective emissivity) of greater than 0.8 in the spectralrange of 7-15 μm in wavelength.

FIG. 3 shows a cross-sectional view of illustrative cooling panel 301absorbing incident radiation in the visible spectrum, in accordance withsome embodiments of the present disclosure.

FIG. 4 shows a cross-sectional view of illustrative cooling panel 401absorbing or reflecting incident radiation in the spectral range of 275nm to 375 nm, in accordance with some embodiments of the presentdisclosure. In some embodiments, the one or more constituent materialsof cooling panel 401 reflect at least 10% of solar intensity present inthe range of 275 nm to 375 nm. In some embodiments, the one or moreconstituent materials of cooling panel 401 absorb at least 10% of solarintensity present in the range of 275 nm to 375 nm.

In some embodiments, a radiative cooling material includes one or moreconstituent materials that are configured to passively cool at a rate ofgreater than 10 W/m2 at 300 K ambient air temperature when exposed tothe sky (e.g., unobstructed by terrestrial structures). In someembodiments, the one or more constituent materials includes a thermalemissivity (e.g., average or effective emissivity) of greater than 0.8in the spectral range of 7-15 μm in wavelength (e.g., infrared lightrange) and relatively strong absorption or reflectance in the spectral275-375 nm (e.g., ultraviolet).

In some embodiments, an outer layer of the material is configured toprovide strong thermal emittance, (e.g. greater than an average of 0.8from 5-15 microns in wavelength range) and high UV absorption (e.g.greater than 0.75 between 300 and 380 nm in wavelength).

In some embodiments, an outer layer is configured to simultaneouslyprovide strong thermal emittance (e.g. greater than an average of 0.85from 5-15 microns in wavelength range) and high UV reflectance (e.g.greater than 0.75 between 300 and 380 nm in wavelength).

In some embodiments, the material is configured to reflect more than 93%of the weighted solar spectrum from 300 nm to 4 μm in free-spacewavelength.

In some embodiments, the material includes discrete planar layers alonga depth dimension. The planar layers are arranged with a top layerdesigned to exhibit strong thermal emissivity (e.g., averaged at greaterthan 0.8 from 5-15 μm in wavelength), with a lower layer designed toexhibit strong solar spectrum reflection from 300 nm to 4 μm. In someembodiments, the material includes an emissivity of at least 0.8 inspectral range of 5 μm to 15 μm, an ultraviolet reflectivity of at least0.5 in the spectral range of 275 nm to 375 nm, an ultravioletabsorptivity of at least 0.75 in the spectral range of 275 nm to 375 nm,or a combination thereof.

In some embodiments, the material is configured to absorb at least someportions of the visible spectrum (e.g., 400-900 nm). In someembodiments, the material has average absorption.

In some embodiments, the material is affixed to a heat exchangerconfigured to cool a fluid (e.g., liquid or gas). FIG. 5 shows across-sectional view of illustrative cooling panel 501 configured toaccept a heat input from a cooling load, in accordance with someembodiments of the present disclosure. In some embodiments, the materialis insulated in an enclosure to enable cooling to temperatures 3° C.below, or further below, an ambient air temperature. FIG. 6 shows across-sectional view of illustrative cooling panel 601 configured toreject 10 W/m2 from a cooling load when the panel is exposed to the sky,in accordance with some embodiments of the present disclosure.

In some embodiments, the material is affixed to the top of a roof andconfigured to provide durable cooling to the underlying structure orbuilding.

In some embodiments, the material is affixed to a road transport vehicleto provide durable cooling to the vehicle while stationary or in motion.

In some embodiments, the present disclosure is directed to achievingradiative cooling using a panel. The panel is configured forfacilitating thermally-generated emissions that originate from a surfacelayer and based on a temperature of the surface layer, with an averagedthermal emissivity greater than 0.8 from 7-15 microns in wavelength ofelectromagnetic spectra. The panel is configured for absorbing orreflecting incident solar light from 275-375 nm to minimize damage dueto sunlight. The panel is configured for reflecting or absorbing therest of the solar spectrum from 375 nm to 4 microns to enable visualcolor. To illustrate, the panel may include an emissivity of at least0.8 in spectral range of 5 μm to 15 μm, an ultraviolet reflectivity ofat least 0.5 in the spectral range of 275 nm to 375 nm, an ultravioletabsorptivity of at least 0.75 in the spectral range of 275 nm to 375 nm,or a combination thereof.

FIG. 7 shows a cross-sectional view of cooling panel 700 including twolayers; a UV absorbing or reflecting layer (e.g., layer 710) and athermally emissive layer (e.g., layer 720), in accordance with someembodiments of the present disclosure. The UV absorbing or reflectinglayer (e.g., layer 710) is configured to prevent UV radiation fromreaching the thermally-emissive layer. The thermally emissive layer(e.g., layer 720) is configured to emit thermal radiation in a spectralrange that corresponds to the panel temperature. Accordingly, coolingpanel 700 shown in FIG. 7 is configured to cool a cooling load whenexposed to the sky.

In an illustrative example, layer 710 may include a single material, anensemble of nanoparticles, an ensemble of microparticles, or acombination thereof to enhance UV reflection, absorption, or both. In afurther illustrative example, layer 720 may include one or more suitablematerials for radiative cooling (e.g., for thermally emitting,reflecting, or both).

FIG. 8 shows a cross-sectional view of cooling panel 800 including twolayers; a UV absorbing or reflecting composite layer (e.g., layer 810)and a thermally emissive layer (e.g., layer 820), in accordance withsome embodiments of the present disclosure. Layer 810, as illustrated,includes alternating layers arranged and configured to enhance UVreflection, absorption, or both. Layers 811, 813, 815, and 817 arecomposed of a first material and layers 812, 814, 816, and 818 arecomposed of a second material. In an illustrative example, alternatinglayers of Si and ZnO may be used to form layers 811-818. It will beunderstood that while layer 810 is illustrated as included eightsublayers (e.g., layers 811-818), any suitable number of materials maybe used, arranged in any suitable number of sublayers.

FIG. 9 shows plot 900 exhibiting several cooling curves, in accordancewith some embodiments of the present disclosure. The abscissa of plot900 is radiative cooler temperature, in units of Kelvin. The ordinate ofplot 900 is cooling power, in units of W/m2. As compared to a standardreflector, the enhanced reflectors of the present disclosure allow forincreased cooling power, thus causing the cooing curve to trend nearerto the case with no solar absorption.

FIG. 10 shows a configurations of cooling panels 1020 and heat exchanger1004, in accordance with some embodiments of the present disclosure.Illustrative cooling system 1000 includes a cooling loop that includespump 1021, cooling panels 1020, and passages of heat exchanger 1004.Heat exchanger 1004 allows heat transfer from a stream of fluid pumped(e.g., by pump 1021) through cooling panels 1020 and cooling load 1051(e.g., which may include a fluid stream).

FIG. 11 shows an illustrative configurations of cooling panel 1101affixed to heat exchanger 1104, in accordance with some embodiments ofthe present disclosure. Cooling panel 1101, as illustrated, includeslayers 1110 (e.g., a UV absorbing or reflecting layer) and layer 1120(e.g., a thermally emissive layer). Cooling panel 1101 is affixed to, orotherwise integrated with, heat exchanger 1104, which includes coolingpassages 1105 though which a fluid flows. In some embodiments, coolingpanel 1101 includes one or more constituent materials. In anillustrative example, cooling panel 1101 may include an outer surfaceconfigured to interact thermally with the atmosphere and with solarradiation. Further, the panel may have a thermal emissivity of at least0.8 in spectral range of 5 μm to 15 μm, with strong ultravioletabsorption or reflection in the spectral range of 275 nm to 375 nm. Insome embodiments, an enclosure may be configured to insulate the panelto enable cooling to temperatures further than 3° C. below an ambientair temperature.

In some embodiments, the panel is configured for integrating the panelwith a heat exchanger to cool a liquid, gas or solid by conductive orconvective heat transfer. For example, the panel may be affixed, bonded,clamped, or otherwise placed in thermal contact with the heat exchangersuch that heat is conducted from heat exchanger to the panel.

In some embodiments, the panel is configured for cooling a refrigerantin a vapor-compression cycle. For example, the refrigerant may be passedthrough a heat exchanger that is in thermal contact with the panel.

In some embodiments, the panel is configured for achieving a coolingrate of greater than 10 W/m2 of net heat rejection at ambient airtemperature during both day and night.

In some embodiments, the panel is configured for cooling a building,structure or vehicle by direct thermal contact with the building,structure or vehicle.

In some embodiments, the panel is configured for employing freeconvective cooling to cool heat loads from above ambient air temperatureto the air temperature.

In some embodiments, the panel is configured for cooling a refrigerantor a fluid from the outlet of a condenser or a fluid cooler,respectively, at least 0.5° C. below the entering temperature.

In some embodiments, a separate layer or film is used to add UVabsorption or reflection.

In some embodiments, zinc oxide (ZnO) is used for the UV absorptionlayer. The ZnO may be in nano-particle form, micro-particle form, a thinfilm, any other suitable form, or any combination thereof.

In some embodiments, multiple (e.g., greater than six) alternating thinlayers of Silicon and ZnO are used to create a UV-reflective top film,even though both materials absorb light in the UV range (e.g. 275-375nm). By using the contrast in refractive index between the twomaterials, UV reflection is achieved.

In some embodiments, multiple (e.g., greater than four) alternating thinlayers of HfO2 and ZnO2 are used to create a UV-reflective top film,even though both materials absorb light in the UV range (e.g. 275-375nm). By using the contrast in refractive index between the twomaterials, UV reflection is achieved.

In some embodiments, nanoparticles and microparticles of ZnO are used toreflect UV light (e.g. 275-375 nm) due to their shape as well as theirrefractive index.

In some embodiments, the UV-reflective or absorbing layers themselvesare strongly thermally emissive (e.g. greater than 0.8 average between5-15 microns).

In some embodiments, the films include diffuse reflectors to preventlight scattering towards objects on the ground or in the surroundings.

In an illustrative example, the material is configured for ultraviolet(UV) reflection and/or absorption to reduce degradation and maintainperformance. For example, in some embodiments, the material includes asequencing of materials such as alternating thin layers of silicon andZinc oxide to help with UV performance and cooling performance. In afurther example, in some embodiments, the material is configured to beresilient to soiling and weathering through micro-structuring of the topsurface. The micro-structuring of the surface, in one embodiment apillar form, enables surface hydrophobicity to allow for water dropletsto easily roll off the top layer of the film.

In some embodiments, a material of the present disclosure is used forautomotive cooling. FIG. 12 shows illustrative configurations 1200,1220, and 1240 of cooling panels affixed to vehicles, in accordance withsome embodiments of the present disclosure. In some embodiments, thematerial is affixed to the exterior of a car (e.g., configuration 1240),truck (e.g., configuration 1220), bus (e.g., configuration 1200),windshield covering, temporary covering, any other suitable exteriorsurface, or any combination thereof. In some embodiments, the materialis affixed to the roofs of automobiles, buses or trucks to reduce thesolar heat gain coming into the vehicles. The materials could also beused as a temporary covering to reduce the solar heat gain coming inthrough windows such as the windshield of a vehicle. In someembodiments, the material is affixed to the roof of an automobile. Inthis form, the film may reduce heat gain of the vehicle thereby reducingthe air conditioning load and fuel consumption of the vehicle. Toillustrate, the film may be applied directed to the vehicle's exterior,or may be applied on a frame structure (e.g., the cooling panel may beintegrated with or affixed to a heat exchanger). In some embodiments,the material is affixed to the roof bed of a truck, which may be, butneed not be, climate controlled. For example, a significant number oftransport trucks are climate-controlled because they carry perishablegoods, pharmaceutical items and other temperature-sensitive commodities.The materials of the present disclosure can be affixed using a pressuresensitive adhesive so that the materials bond easily to the surface thatit is attached to. The materials of the present disclosure may beconfigured to reduce heat gain of the vehicle, thus reducing coolingload and improving fuel consumption. In some embodiments, the materialis affixed to the top part of the roof of a bus. For example, thecooling film may be able to reduce the bus's solar heat gain, airconditioning load, fuel consumption, carbon footprint and greenhouse gasemissions.

FIG. 13 shows a side view and top view of a greenhouse havingillustrative cooling panels 1301 affixed to the roof, in accordance withsome embodiments of the present disclosure. In some embodiments, thecooling film may be applied directly to glass facades on greenhousestructures. For example, the film may be cut into strips or othersuitable pieces to allow some light to come through the glass. The filmwould reflect other light out and also cool the glass it is in contactwith.

FIG. 14 shows a side view of electrical system 1400 having illustrativecooling panels 1401, 1411, and 1421 affixed to respective electricalcabinets 1402, 1412, and 1422, in accordance with some embodiments ofthe present disclosure. In some embodiments, a material of the presentdisclosure is used for electronics cooling (e.g., electronic cabinets,other housing of outdoor electronic equipment, batteries). In someembodiments, a cooling film is used as an exterior surface to augmentheat rejection of passive convective surfaces. Such surfaces may befound in, for example, cell phone tower equipment, outdoor powerelectronics, solar inverters, electrical cabinets, transformers andbattery storage systems. The cooling film may be used to replace fins orcould otherwise enhance the performance of fins to allow for higherenergy density electronics to be deployed per outdoor case. The coolingfilm may be configured to reduce solar heat gain to external cabinets,enhancing the amount of cooling possible by outdoor surfaces. In someembodiments, the cooling film may be combined with thermal storage toensure that the cabinets never go above a preset internal temperature of40° C. For example, such cabinets would require zero electricity forcooling and cooling would be completely passive. In some embodiments,the surface may be tilted to ensure that dirt does not accumulate on thefilm.

FIG. 15 shows a side view of outdoor structure 1502 having illustrativecooling panel 1501 affixed to a roof, in accordance with someembodiments of the present disclosure. In some embodiments, a materialof the present disclosure is used for outdoor shade cooling of astructure (e.g., applied to an outdoor shade structure such as busshelter or canopy). In some embodiments, the material or cooling panelsincluding the material is affixed to the sky-facing part of a shadestructure such as, for example, a bus shelter or a canopy. In anillustrative example, the material may be applied directly to thestructure during manufacturing of the structure or canopy. In a furtherexample, the material may be applied once the structure has been builtand deployed. The cooling film provides passive cooling to the shadestructure, thus reducing solar gains and an urban heat island effect ofshade structures by reflecting sunlight and radiating heat to the sky.

In some embodiments, the material of the present disclosure, or filmsthereof, may be applied to curved surfaces, rough surfaces, or otherwisesuitably non-planar surfaces. For example, a cooling film may be appliedto flat and simply curved surfaces. The cooling film exhibits the mostcooling when angled directly towards the sky. In some circumstances,however, the film may be angled slightly away from the sky while stillmaintaining performance (e.g., high reflectivity and emissivity). Forexample, one side of the film may include a pressure sensitive adhesivethat allows the film to be applied easily to surfaces.

FIG. 16 shows a side view of containerized living unit 1602 havingillustrative cooling panels 1601 affixed to the exterior ofcontainerized living unit 1602, in accordance with some embodiments ofthe present disclosure. In some embodiments, a material of the presentdisclosure is used for cooling modular spaces (e.g., a containerizedliving unit (CLU), mobile home, trailer, temporary storage facility). Insome embodiments, the material is affixed to an outward-facing portion(e.g., a steel portion) of the structure. Examples of structures includecontainer living units, mobile homes, mobile bathrooms, trailers andtemporary storage facilities. To illustrate, shipping container housingis becoming increasingly popular for both military and civilian use.When applied to the steel surface, the cooling film may provide coolingto the underlying structure of the CLU. Cooling is accomplished byreflecting 95% or more of incident sunlight and emitting infrared lightto the sky to reject heat from the CLU. To provide additional cooling,the cooling film may also be applied to the outward facing sides of theCLU. By applying the cooling film to passively cool the CLU, the CLU maybe able to reduce the use of other forms of energy, such as diesel fuel,to provide cooling in hot and/or dry climates.

FIG. 17 shows configurations 1700, 1710, and 1720 of cooling panels usedto cool aspects of a vending machine, in accordance with someembodiments of the present disclosure. Configuration 1700 shows coolingpanels 1701 arranged as a condenser for vending machine 1702. Coolingpanels 1701 may be affixed to a heat exchanger or coupled to a heatexchanger via plumbing, in order to cool a fluid of vending machine1702. Configuration 1710 shows cooling panels 1711 arranged as a roofstructure (or otherwise affixed to a roof structure) and condenser forvending machine 1712 (e.g., with occupant region 1713). Cooling panels1711 may be affixed to a heat exchanger or coupled to a heat exchangervia plumbing, in order to cool a fluid of vending machine 1712. In someembodiments, a material of the present disclosure is used forrefrigerated vending system cooling (e.g., applied to outdoorrefrigerated vending machines). In some embodiments, the cooling filmmay be included in panels used as a condenser to outdoor vendingmachines. For example, the outdoor vending machines may have somerefrigeration capabilities used to keep drinks or food cool. In someembodiments, the panels may be used with or combined with a shadestructure for both people and the vending machine. In some embodiments,a refrigerant could flow directly through the panels and in otherembodiments, a secondary fluid loop would exist to cool refrigerant inthe unit.

FIG. 18 shows two illustrative configurations of cooling panels used tocool aspects of a swimming pool, in accordance with some embodiments ofthe present disclosure. In some embodiments, cooling system 1800 mayinclude cooling panel arrays 1820, 1821, and 1822 coupled to fluidconduits 1805 and 1806. In some embodiments, cooling system 1800 mayinclude a pump to aid in moving fluid though conduits 1805 and 1806.Cooling system 1800 may be sized based on a thermal load (e.g., swimmingpool 1010). For example, as illustrated, cooling system 1800 includesthree cooling panel arrays (e.g., cooling panel arrays 1820, 1821, and1822), but could optionally include one, two, three, or more than threecooling panel arrays. Fluid conduits 1805 and 1806, as illustrated, arecoupled to passages of cooling panel arrays 1820, 1821, and 1822, whichare arranged in parallel. In some embodiments, not illustrated, coolingsystem 1800 may include thermal storage, multiple pumps, flow controlvalves, sensors (e.g., to sense pressure, temperature, or differencesthereof), bypass flow paths, de-aerators, fill ports, fluid-compatiblefittings (e.g., of any suitable type), manifolds, distribution blocks,any other components not illustrated in FIG. 18 , or any combinationthereof. Configuration 1850 includes pool cover 1851, which includes acooling film in accordance with present disclosure, arranged over pool1852 to provide cooling during the day, night, or both. In someembodiments, a material of the present disclosure is used for poolcooling. In some embodiments, panels including a cooling film may beused (e.g., in an open loop) to directly cool water contained in aswimming pool. For example, the system may include a pump, strainer, andnominally 2 m2 to 3 m2 of panel for every 100 gal of water in the pool.In some embodiments, the cooling film would be applied as a cover to thepool to prevent the pool from absorbing heat from the sun (e.g., in themiddle of the day) and also cooling the pool during the day and at nightby emitting infrared heat.

The foregoing is merely illustrative of the principles of thisdisclosure and various modifications may be made by those skilled in theart without departing from the scope of this disclosure. Theabove-described embodiments are presented for purposes of illustrationand not of limitation. The present disclosure also can take many formsother than those explicitly described herein. Accordingly, it isemphasized that this disclosure is not limited to the explicitlydisclosed methods, systems, and apparatuses, but is intended to includevariations to and modifications thereof, which are within the spirit ofthe following claims.

What is claimed is:
 1. A cooling panel comprising: an outer surfaceconfigured to interact thermally with an atmosphere and with solarradiation; and one or more constituent materials causing the coolingpanel to comprise: an emissivity of at least 0.8 in spectral range of 5μm to 15 μm, and an ultraviolet reflectivity of at least 0.5 in thespectral range of 275 nm to 375 nm, or an ultraviolet absorptivity of atleast 0.75 in the spectral range of 275 nm to 375 nm.
 2. The coolingpanel of claim 1, wherein the one or more constituent materials arecapable of achieving a cooling rate of 10 W/m2 when exposed to the skyat a 300 K ambient air temperature.
 3. The cooling panel of claim 1,wherein the one or more constituent materials comprise a thicknessnormal to the outer surface.
 4. The cooling panel of claim 1, whereinthe one or more constituent materials are capable of reflecting greaterthan 93% of the weighted solar spectrum from 300 nm to 4 μm infree-space wavelength.
 5. The cooling panel of claim 1, wherein the oneor more constituent materials are capable of absorbing at least some ofthe visible spectrum of 400 nm to 900 nm.
 6. The cooling panel of claim1, further comprising lateral structuring of the outer surface toenhance surface wettability for hydrophobic behavior.
 7. The coolingpanel of claim 1, further comprising a plurality of discrete planarlayers along a depth dimension.
 8. The cooling panel of claim 1, whereinthe one or more constituent materials comprise at least one of ZnO, Si,HfO2, or ZnO2.
 9. The cooling panel of claim 1, wherein the one or moreconstituent materials comprise: a first layer configured to reflect orabsorb ultraviolet radiation; and a second layer configured to emitthermal radiation in a spectral range that corresponds to a temperatureof the cooling panel.
 10. The cooling panel of claim 9, wherein: thefirst layer is arranged between the atmosphere and the second layer; andthe first layer is configured to prevent UV radiation from reaching thesecond layer.
 11. The cooling panel of claim 9, wherein the first layercomprises a composite layer comprising alternating layers of a firstmaterial and a second material.
 12. The cooling panel of claim 9,wherein the first layer comprises alternating layers of Si and ZnO. 13.The cooling panel of claim 9, wherein the first layer comprisesalternating layers of HfO2 and ZnO2.
 14. An apparatus comprising: acooling panel configured to interact thermally with an atmosphere andwith solar radiation, the cooling panel comprising: an emissivity of atleast 0.8 in spectral range of 5 μm to 15 μm, and an ultravioletreflectivity of at least 0.5 in the spectral range of 275 nm to 375 nm,or an ultraviolet absorptivity of at least 0.75 in the spectral range of275 nm to 375 nm; and cooling passages configured to receive heat from afluid.
 15. The apparatus of claim 14, wherein the cooling panel iscapable of reflecting greater than 93% of the weighted solar spectrumfrom 300 nm to 4 μm in free-space wavelength.
 16. The apparatus of claim14, wherein the cooling panel is capable of absorbing at least some ofthe visible spectrum of 400 nm to 900 nm.
 17. The apparatus of claim 14,wherein the cooling panel comprises a plurality of discrete planarlayers along a depth dimension.
 18. The apparatus of claim 14, furthercomprising one or more constituent materials comprising at least one ofZnO, Si, HfO2, or ZnO2.
 19. The apparatus of claim 14, wherein thecooling panel comprises: a first layer configured to reflect or absorbultraviolet radiation; and a second layer configured to emit thermalradiation in a spectral range that corresponds to a temperature of thecooling panel.
 20. The apparatus of claim 19, wherein: the first layeris arranged between the atmosphere and the second layer; and the firstlayer is configured to prevent UV radiation from reaching the secondlayer.